In U.S. Letters Patent Nos. 3,923,381, 3,957,031 and 4,002,499, there are given examples of a particular type of radiant energy concentration and collection device generally known as a trough-shaped nonimaging collector. Such concentration devices take radiant energy which strikes an entrance aperture and concentrates it onto an exit surface of smaller area than the entrance aperture. Reflective side walls of particular contour extend between the entrance aperture and the exit surface. There is generally positioned at the exit surface an energy absorber.
Prior art methods of constructing a trough-shaped collector include use of extruded aluminum side walls, aluminum sheet rolled into the proper contour or metallizing of thick solid plastic substrates. All these methods are characterized either by their high cost of manufacture or large weight. The cost arises from the materials used and the means required to manufacture the devices. Large weight is detrimental to the commercial potential because of the increased handling and shipping costs. Thin plastic has been suggested as a possible substitute material. However, use of thin plastics has not been possible because of the inability of thin plastics to withstand the high temperature of the absorber and to provide sufficient structural strength for long life and to maintain the precise alignment of the elements of a trough-shaped collector so that energy is efficiently collected.
It is therefore an object of this invention to provide an improved radiant energy concentration and collection assembly.
Another object of this invention is to provide a light-weight, inexpensive trough-shaped solar radiant energy collector utilizing thin-walled plastic.